Design an Angular 2+ shopping module PART 3

Follow up from PART 2 we now need to fill the blank of payment implementation which is mostly handled by 3rd party payment services, but we still need an adapter or api or something to communicate with these external services.

Design an Angular 2+ shopping module PART 2

Now I'll need an user story to figure out what services and functionalities I need.

The user story...

1. When I see an item, whatever is for sale, it's a Product. I can add it to my shopping cart.
2. I can quick link to my shopping cart wherever in the APP.
3. I can change the quantity of purchased product
4. It'll require my contact information to complete the order.
5. I have to choose a payment method to complete the order.
6. I have to follow the instruction of payment method to complete payment.
7. When payment confirmed, I need to be noticed that the order is confirmed paid.
8. I can review the order detail anytime.
9. I can check a list of all my orders.

Design an Angular 2+ shopping module PART 1

I should have done this way before my code of this module being tangled like a hell.

A shopping module...

What the fudge is it ?

It's an Angular 2+ shopping module, which is meant to be integrated into any Angular 2+ APP and enabling users to purchase items in the APP, to create an order, and to pay for that order.